Context: Saiki borrows his father's glasses without permission.
oi~~ megane kaeshite yo~~ オイ～～眼鏡返してよ～ Heey, give [my] glasses back~~
gaman shite kure chotto me ga "san" ni naru dake daro 我慢してくれちょっと目が「３」になるだけだろ Please endure [it], [all that will happen is that] [your] eyes will become "threes."
In anime, eyes are drawn like 3's sometimes when a character that needs glasses isn't wearing them.
megane ga nai to hotondo mienai-n-da yo~~ 眼鏡がないとほとんど見えないんだよ～ Without [my] glasses [I] almost can't see.
